Confocal Raman Imaging-40-200

CCD cts
20WITec Raman
Spectroscopy Solutions

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www.witec.deWITec UHTS

Ultra-High Throughput Spectrometers
for Raman Microscopy

The WITec ultra-high throughput spectrometer (UHTS) series consists of exceptionally
flexible and precise devices that meet the demands of cutting-edge confocal Ramanimaging. For optimized performance, excitation sources, spectrometers, optics andcameras have to be carefully matched. The WITec UHTS design approach acknowledges
this by employing a series of lens-based on-axis spectrometers with a choice of focal
lengths, gratings and optics perfectly matched to the selected excitation wavelength.
The spectrometers can be individually configured for specialized requirements
and a wide variety of applications. No other manufacturer can provide such a highlevel of flexibility.

Ultra-high throughput

CCD
cameraUHTS spectrometers are specifically designed forchallenging Raman imaging and spectroscopy applications
with intrinsically low light intensities.
Optical fiber
entrance

Ultra-fast acquisition times

Using the UHTS for data collection, the acquisition
time for a single Raman spectrum can be reduced
to below one millisecond, providing essential
benefits in confocal Raman microscopy wherecommonly thousands of Raman spectra mustbe acquired.

Ultra-sharp and symmetric peak shape

WITec UHTS spectrometers deliver outstanding spectral
and imaging quality. Symmetric peak shapes are ensured
by design with coma- and astigmatism-free optics.

02Ultra-customizable:
triple-grating turret

An automated three-grating turretfacilitates the flexible integration andcombination of individual gratings.
Automated switching from one gratingto another to accommodate varying
experimental requirements has neverbeen easier.

Focusing lens system

The Raman spectrometers of the UHTS
series are available in different focal
lengths to accommodate multiple
laser excitation wavelengths and spectral
resolution requirements for the mostdemanding Raman imaging experiments.

Automated turret withup to three gratings

Influence of grating onspectral resolution
Collimating lenssystemUltra-configurable: several focal
lengths and grating types

Influence of focal length on
spectral resolution
ShortGrating
lowdispersion

CCD chip

Grating

CCD chipIncoming light

Incoming lightLong

Grating
highdispersion

CCD chip

Incoming light

Grating

Incoming light

Grating dispersion and focal length influence signal intensity, detectable spectral range and resolution.

Spectral and pixel resolution facts

The resolving power of a spectroscopic system depends on
focal length, grating groove density and pixel size of theCCD camera used for detection. The overall goal is to findthe ideal balance with regard to acquisition time, signalto-noise ratio and spectral resolution. Increasing the focal
length or the number of grooves per millimeter on thegrating increases the spectral resolution, but reduces thesignal per pixel as the light is spread out over a larger area.

With the ultra-high throughput of the WITec spectrometer
series, this signal loss is minimized and the full spectral
bandwidth is retained through integrated spectral stitchingprocedures. As a result, highly-resolved spectra can beobtained from the full relevant spectral range up to a pixel
resolution of 0.1 relative wavenumbers (cm-1).

WITec Raman Spectroscopy Solutions | 03

WITec UHTS Series
The lens-based spectrometers of the UHTS series allow for the highest throughput and are
therefore suitable for high speed and high resolution Raman imaging. Gratings have theiroptimal reflectivity in only relatively small spectral ranges, leading to dramatic signal loss
when used outside of those parts of the spectrum. Therefore WITec optimized the UHTS
spectrometers for specific wavelength ranges. Customers can choose from a variety of focal
lengths and gratings to match individual requirements in terms of spectral range andresolution.

SPECTRAL RANGE
01

UHTS 300 VIS

02UHTS 600 VIS

03 UHTS 400 UV - VIS
04

Broadband UHTS 300 VIS - NIR

05

UHTS 400 NIR

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400 nm

500 nmUV

03
04

600 nmVIS

UHTS 400 UV-VISWith an optical system tailored for UV
measurements, the UHTS 400 UV-VIS
is the optimal solution for excitation
wavelengths from 355 to 588 nm.

700 nm

UHTS 300 IR
900 nm04

1100 nm1300 nm

1500 nm1700 nm

NIR

UHTS 300 VIS-NIR
Applications requiring broadband excitationfrom the visible to the near-infrared can greatly
benefit from the UHTS 300 VIS-NIR.
This spectrometer is well suited for multiple
laser configurations between 532 nm and830 nm while maintaining the advantagesof the UHTS series.

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UHTS 300 VIS
For excitation in the visible range the UHTS
300 VIS provides outstanding dispersive
peak separation capabilities. The focal
length of 300 mm is in accordance withthe required sensitivity for demanding
Raman imaging applications.

WITec lens-based spectrometers cover the full spectral
range with specialized variants, providing the highest
throughput for ultra-fast and low light-level Raman
imaging applications. All UHTS spectrometers feature
an optical fiber port and a software-controlled triple-grating
turret. By using high-throughput and high-quality opticalcomponents in the beam path, overall sensitivity issignificantly improved.

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UHTS 400 NIR
In the near-infrared regime the use of NIRoptimized optical components is essential
for high-throughput spectral acquisition.
A focal length of 400 mm, a specialized set ofgratings and state-of-the-art deep depletion
CCD technology combine to form an ideal
solution for NIR Raman spectroscopy.

02

UHTS 600 VIS
The UHTS 600 features an extended focal
length of 600 mm for increased spectral
resolution, which allows closely adjacentpeaks to be resolved more readily. Thisnew addition to the UHTS line enhances
spectral resolution without compromisingthroughput, therefore acquisition times
remain unparalleled.

The WITec UHTS series for multiple laser excitation
offers the most flexible and advanced solution for
hyperspectral Raman microscopy. For individual
excitation requirements not listed, WITec can provide
a variety of proven and installed spectroscopy solutions.
Please discuss your specific needs with the WITec
Raman imaging specialists to determine the best
configuration for you.

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UHTS 300 IR
The UHTS 300 IR covers the excitation range
from 800 to 1700 nm, featuring infraredoptimized optical components, gratingsand detectors for highly precise andaccurate Raman and photoluminescence
experiments.

WITec Raman Spectroscopy Solutions | 05

WITec CCD Detectors
Capability, Versatility and Expandability for
Raman Spectroscopy – Optimized Today,
Ready for Tomorrow
CCD cameras are optimized for certain wavelength ranges, beit UV, visible light or NIR. That must be considered when
configuring a UHTS spectrometer setup to meet sophisticatedrequirements for quick and sensitive Raman imaging.
Several types of CCD cameras with quantum efficienciesexceeding 90% can be integrated with the UHTS series.

010206

Front-illuminated (FI) CCD
A front-illuminated CCD is characterized bya broad range of possible applications andwavelengths, generally oriented toward budgetconscious but advanced experimental setups.

Electron-multiplying (EM) CCD
4 µm

Currently, an EM CCD comes as close as possible
to an ideal shot noise-limited detector. This
type of camera provides the most advanced
readout capabilities for low light level detection
or ULTRA-FAST RAMAN IMAGING®necessaryfor sophisticated and leading-edge Raman
applications. Readout speed can be as fast as
760 µs per spectrum (1300 spectra/s) and darkcurrent as low as 10-4 electrons/pixel/s.

Confocal Raman image of toothpaste.
200 x 200 pixels, 40,000 spectra,
acquisition time per spectrum:
760 μs, per image: 40 s.

03Open Electrode (OE) CCD
The open electrode CCD is a front-illuminated camerathat enables the acquisition of almost the entire
spectral bandwidth and is particularly well suited tomeasurements in the UV. In order to achieve state-of-theart signal-to-noise ratios it features a low dark-current
and multi-purpose camera functionality.

040506

Low Dark-current Deep Depletion CCD
Near-infrared (NIR) spectroscopic Raman and photoluminescence(PL) measurements require specialized CCD detectors toprevent the spectral data from being influenced by “etaloning,”
an effect that occurs when the Si-CCD chip materials become
increasingly transparent to light at longer wavelengths.
With the low dark-current deep depletion technology provided
by this detector, critical NIR and PL experiments can be
performed with minimal signal loss.

Back-illuminated (BI) CCD
With a quantum efficiency of 95% or more, backilluminated CCD cameras set the industry standard for
efficient Raman signal detection in the visible range.
Compared to a front-illuminated CCD, they offer twice thequantum efficiency and are therefore suitable for precise
and sensitive FAST RAMAN IMAGING® at the highest
lateral resolution. UV-optimized versions are also available.

InGaAs linear array detector
For scattering experiments above the Si-bandgap at
approximately 1100 nm, WITec supplies state-of-the-art
Indium-Gallium-Arsenide (InGaAs) linear array detectorsthat allow for spectral imaging in the IR up to 1700 nm
with peak quantum efficiencies near 90%.

Silicondioxide
Incoming lightGateSilicon

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Others uponrequestWITec Raman Spectroscopy Solutions | 07

Proven Measurement Powerfor Demonstrable and Consistent
Raman Imaging Results

WITec spectroscopic systems enable the acquisition of Raman spectra,images, depth profiles and 3D images with exceptional spectral andspatial precision. This proven performance in speed, sensitivity andresolution is available without compromise or caveat, in your facility.

Symmetric Peak Shape: CyclohexaneAB(A) Raman spectrum of cyclohexane acquired with the UHTS 300 VIS. (B) Zoom-in at the 1030 relative wavenumbers (cm-1) peak region.
In addition to the measured spectra (blue) a Lorentzian-fitted curve is displayed (red). The almost perfect match of the measured spectrawith the theoretically predicted curve shows the high accuracy of the measurement.

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High-performance Raman Imaging Application:
CCl4 – Water-Oil Emulsion
ACBD(A) 3D confocal Raman image of an emulsion with corresponding Raman spectra shownin (B) Green: alkane; blue: water; yellow: CCl4 + oil. Image parameters: 100 x 100 x 10 µm3
scan range, 0.06 s integration time per spectrum, 532 nm excitation wavelength.
(C) Zoom-in image with high spectral resolution. Image parameters: 10 x 10 µm2,0.08 s integration time per spectrum, UHTS 600 spectrometer, 1800 g/mm grating.
(D) Due to the high spectral resolution of the spectroscopic system the CCl4 bands
at around 460 relative wavenumbers (cm-1) can be clearly resolved.

Sensitivity: Raman Spectrum 4th Order of Silicon
3rd order of Si

O2

4th order of SiN2The ability to resolve the peak of the 4th order band of Si is widely considered to be ameasure of the sensitivity of a Raman spectroscopy system. The spectrum aboveshows the 4th order Si peak acquired with the UHTS 300 VIS equipped with an EM CCD.
No data post-processing other than cosmic ray removal was applied.
The very high signal-to-noise ratio along with the low intensities of the O2 and N2 peaks
indicate the true confocality of the system as the detected signals from the environment(e.g. air) are extremely low, showing that the contribution from out-of-focus light iseffectively blocked by the pinhole.

WITec Raman Spectroscopy Solutions | 09

Confocal Raman Imaging

WITec Raman Spectroscopy Solutions
WITec Raman imaging systems combine extremely sensitive confocal
microscopes with ultra-high throughput spectrometers for unprecedented
capability in chemical characterization. Our Raman imaging specialists areready to assist in defining an optimized system for individual applications
and budget requirements. Even future ambitions can be taken into accountas WITec systems are fully upgradeable, scalable and able to incorporate
additional excitation wavelengths, scan stages and microscopy techniques.
If your scientific approach changes, WITec systems can change with you.

Raman Imaging Benefits• Detailed analysis of chemical compound
distribution, amorphous/crystalline forms
and material stress properties• Lateral spatial resolution down to ~200 nm(diffraction limited)• 3D chemical imaging due to confocal setup• Nondestructive• Minimal, if any, sample preparation required• Correlative imaging readily available(AFM, SNOM, TERS, SEM)

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The WITec UHTS series can be equipped witha selection of market-leading high-quality
spectroscopic CCD detectors. With chip sizes andquantum efficiencies matched to the opticalcomponents of the spectrometer, setting thebenchmark for FAST- and ULTRA-FAST RAMAN
IMAGING® has never been easier.

WITec Raman Spectroscopy Solutions | 11

Confocal Raman imaging system alpha300 R
with UHTS 300 spectrometer

WITec Headquarters
WITec GmbH
Lise-Meitner-Straße 6D-89081 Ulm . Germany
Phone +49 (0) 731 140700
Fax +49 (0) 731 14070200
info@WITec.de
www.WITec.de

WITec North America

WITec Instruments Corp.
130G Market Place Blvd
Knoxville . TN 37922 . USA
Phone 865 984 4445
Fax 865 984 4441
info@WITec-Instruments.com
www.WITec-Instruments.com

WITec South East Asia

WITec Pte. Ltd.
25 International Business Park
#03-59A German Centre
Singapore 609916
Phone +65 9026 5667
shawn.lee@witec.biz

WITec China

WITec Beijing Representative Office
Unit 507, Landmark Tower 1
8 North Dongsanhuan Road
Beijing, PRC., 100004
Phone +86 6590 0577
shuo.ding@witec-instruments.com

WITec Japan

WITec K.K.
KSP W713B Sakado 3-2-1 Takatsu-ku
Kawasaki-shi Kanagawa 213-0012
JapanPhone +81 44 819 7773
keiichi.nakamoto@witec-instruments.biz